io_ring_buffer_epoll.hpp

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// =========================================================================
//   CLASS     : IoRingBuffer
//   METHOD    : registerBuffer
// =========================================================================
template <size_t Count, size_t Size>
int join::IoRingBuffer::registerBuffer (uint16_t group, LocalMem::Allocator<Count, Size>& arena)
{
    static_assert (isPow2 (Count), "buffer count must be a power of two");
 
    if (JOIN_UNLIKELY (_base != nullptr))
    {
        lastError = make_error_code (Errc::InUse);
        return -1;
    }
 
    if (JOIN_UNLIKELY (!arena.reserveAll ()))
    {
        lastError = make_error_code (Errc::InUse);
        return -1;
    }
 
    _base = static_cast<char*> (arena.getPtr (0));
    _release = [&arena] () {
        arena.releaseAll ();
    };
    _size = Size;
    _count = Count;
    _group = group;
    _free = 0;
 
    for (uint16_t bid = 0; bid < _count - 1; ++bid)
    {
        *static_cast<uint16_t*> (get (bid)) = bid + 1;
    }
 
    *static_cast<uint16_t*> (get (_count - 1)) = _none;
 
    return 0;
}
 
// =========================================================================
//   CLASS     : IoRingBuffer
//   METHOD    : unregisterBuffer
// =========================================================================
inline int join::IoRingBuffer::unregisterBuffer () noexcept
{
    if (_base == nullptr)
    {
        return 0;
    }
 
    _release ();
    _release = nullptr;
    _base = nullptr;
    _size = 0;
    _count = 0;
    _group = 0;
    _free = _none;
 
    return 0;
}
 
// =========================================================================
//   CLASS     : IoRingBuffer
//   METHOD    : select
// =========================================================================
inline int join::IoRingBuffer::select () noexcept
{
    if (JOIN_UNLIKELY (_free == _none))
    {
        return -1;
    }
 
    uint16_t bid = _free;
    _free = *static_cast<uint16_t*> (get (bid));
 
    return bid;
}
 
// =========================================================================
//   CLASS     : IoRingBuffer
//   METHOD    : recycle
// =========================================================================
inline void join::IoRingBuffer::recycle (uint16_t bid) noexcept
{
    *static_cast<uint16_t*> (get (bid)) = _free;
    _free = bid;
}